The research aimed at finding out and observing how far the influence of the knowledge of the society about iB brand was, towards the decision of the customer to use the product of sharia bank (case study in Yogyakarta society). The research was quantitative descriptive in nature, by using primary data, with the result (answer) of questionnaire from 100 respondents. The analysis conducted was simple linear regression analysis. The research did the validity and reliability test towards questionnaire data. The result of the research showed that from the simple linear regression result, the value of R coefficient was 0.0730 or 73 percent showed that the variable of the influence of the society knowledge towards iB had a high relationship with the variable of customer decision